Transit concrete mixer



NOV. 18, 1952 R CASTENDYCK 2,618,472

TRANSIT CONCRETE MIXER Filed May 1, 1950 3 Sheets-Sheet 1 23 I B :1 31B1 E Z0 51 \z i I f '2 20 I i .90 25 u 4 Q 'J-sss R. CHSTENDYCK, BY

Nov. 18, 1952 2,618,472

J. R. CASTENDYCK TRANSIT CONCRETE MIXER 3 Sheets-Sheet 2 Filed May 1,1950 INVENTOR.

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1952 .1. R. CASTENDYCK 2,618,472

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Patented Nov. 18, 1952 UNITED STATES ATENT OFFICE.

2,618,472 TRANSIT CONCRETE MIXER JesscR. Castendyck, Downey, Calif.Application May 1, 1950, Serial No. 159,316

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My invention relates to concrete mixing apparatus and more particularlyto transit mixers in which a mixing drum is mounted on a. motor vehicleto receive a load of aggregates, cement and water, at a supply sourceand mix the batch while the vehicle is enroute so that upon arrivalatthe job the concrete is ready for use.

Specifically, although not necessarily, my invention has reference tothat type of transit mixer in which the drum as rotatably mounted on thevehicle is inclined upwardly toward. the rear end of the vehicle, andits high end is open so that both feeding and discharging of theconcrete may be effected at that end of the drum. Fixed in the drum areblades which, under rotation of the drum in one direction, operate tomix and feed the aggregates toward the closed forward end of the drum.This operation of the blades takes place durin transit of the vehicle tothe job. Upon arrival at the job the drum is rotated in the otherdirection, resulting in the blades operating to discharge the. concretefrom the rear open end of the drum.

During transit of this type of mixer to a job, spillage and consequentloss of concrete occurs from the rear open end of the drum. This is dueto the sudden forward motions to which the drum is subjected resultantof quick starting and acceleration of the truck, as well as to upwardtilting of the drum as when the truck is ascending a steep grade and itsspeed is suddenly increased. To prevent such spillage the open end ofthe drum of present mixers is provided with a closure which is mountedindependently of the drum to open or close the drum opening. Not onlydoes this closure and the actuating means therefor add materially to thecost of the mixer, but it requires frequent repair since, when in closedposition, although in contact with the drum, it cannot rotate with thedrum and thus is subjected to constant wear which makes it difficult toprevent leakage of the liquid content of the concrete from the drum andthereby maintain the original quality of the concrete.

or course, in the helical bladed mixers without closures, spillage ofconcrete invariably occurs during transit in spite of the inward feedingaction of the blades, since the spacing of the blades from each otherprovides an unobstructed passage generally axially coincident with thedrum opening, through which the concrete is free to be thrown when thedrum is subjected to sudden forward movement or when ascending a steepinclination, or both.

To minimize spillage, usersof such mixers reduce the yardage ofaggregates supplied to a mixer considerably below the maximum capacityof that mixer. Naturally thisv greatly reduces the pay load of themixer.

It is the purpose of my invention to provide a transit concrete mixer ofthe type described, which eliminates the need of a closure and yetcompletely prevents spillage of the concrete therefrom during transit,regardless of'the in- 2 tensity of the sudden forward motions of themixer, the steepness of any inclination ascended thereby, or anycombination of the two. In achieving this result one is enabled toincrease the concrete carrying capacity of a mixer to its maximumwithout spillage.

In the attainment of thisnon-spillage function in a mixer having helicalmixing blades, the blades, preferably. at pointsv adjacent the open. endof the drum, are provided with elements which co-act to form a dam inthe passage between the blades that prevents the aggregates from beingthrown rearwardly within and outwardly of the drum, while atthe sametime not interfering with the normal feeding of the aggregates by theblades when charging the drum.

When discharging concrete from thedrum under reverse rotation of theblades, these damming elements serve to prevent the concrete fromspilling off of the blades, and thus tend to pack it adjacent the drumopening, resulting in a positive and rapid discharge of. the concretefrom the drum, and thereby lessening the time normally required to emptythe drum.

I will describe only two forms of mixers, each embodying my invention,and will then point out the novel features thereof in claims.

In the accompanying drawings:

Fig. 1 isv a view showing, in side elevation, a truck having mountedthereon one form of concrete mixer embodying my invention.

Fig. 2 is an enlarged vertical longitudinal sectional view of the mixingdrum and adjacent parts of the mixer shown in Fig. 1.

Fig. 3 is an end elevational view taken on the line 3-3 of Fig. 2'.

Fig. 4 is a vertical sectional view taken on the line i-4 of Fig. 2.

Fig. 5 is a vertical sectional view taken on the line 55 of Fig. 2.

Fig. 6 is a vertical sectional view taken on the line 65 of Fig. 5.

Fig. 'l is a fragmentary end elevational view of oneof the blades shownin Fig. 2 and illustrating one form of damming element embodying myinvention.

Fig. 8 is a fragmentary side elevationalview of the blade shown in Fig.'7 and the accompanying damming element.

Fig. 9 is a fragmentary vertical sectional view similar to Fig. 2 andshowing another form of damming element embodying my invention.

Fig. 10 is a vertical sectional view taken on the line Iii-l0 of Fig. 9.

Fig. 11 is a view similar to Fig. 7 and illustrating one of the dammingelements shown in Fig. 10.

Referring specifically to the drawings, T designates a motor truck, onthe frame F of which a mixing drum D is. mounted for rotation in eitherdirection about an axis which is inclined upwardly to the rear end ofthe truck as is conventional to give a high point of discharge and thusfacilitate distribution of the concrete at the job over a greater area.

The drum D has an intermediate cylindrical portion l5, a front endconical portion 16, and a rear end conical portion l! which, at its rearend, is formed with an opening l8 through which the drum may be chargedwith aggregates through a hopper I9 fixed on the frame F by asuperstructure S and extending into the opening.

For mounting the drum D to rotate about an axis inclined upwardly to itsrear end, I preferably employ a shaft 20 journalled in a support 2| onthe frame F. The upper end of this shaft is fixed to the adjacent drumend, and it carries a sprocket 22 about which an endless chain 23 istrained and adapted to be driven by any suitable means (not shown) forselectively rotating the drum in either direction.

The drum D at the rear end of the cylindrical portion l has fixedthereto a bearing rim 24, and rollers 25 engage the rim for rotatablysupporting the drum at this point. The rollers are mounted in suitablebrackets 26 (see Fig. 3) and the drum is confined on the rollers by ayoke 21 fixed to the frame F and extending over the drum.

Fixed to the inner Wall of the drum D in any suitable manner, such as bywelding, is a main helical blade B which extends preferably from a pointadjacent the closed end of the drum (see Fig. 2) to and through thecylindrical and rear conical portions [5 and IT. The greatest width ofthe blade is in the drum portion [5, and it is uniform, while in thedrum portions l6 and II it is reduced in width to correspond to thereduction in internal diameter of these portions.

Also fixed within the drum, as by welding, is a second and subsidiaryblade Bl which starts at a point within the cylindrical portion [5 andends at or adjacent the opening I8. That part of the blade Bl within theportion I5 is preferably of the same width as that part of the blade Bin the same drum portion, and in the drum portion ll its width isdecreased to the same degree as the corresponding part of the blade B.

Resultant of the afore-described arrangement of blades B and BI there isnaturally provided between them a passage P which is coincident with theaxis of the opening l8. Such a passage is of necessity formed in allmixers having helical blades so arranged, and it is through this passagethat spillage of the concrete or its aggregates occurs through theopening 58 during transit of the mixer to a job.

In Figs. 1 to 5, '7 and 8 is illustrated one means for positivelypreventing such spillage, particularly when the drum is loaded withaggregates having a high slump characteristic. This means comprisesdamming elements E which are secured to or formed integral with theblades B and BI at opposite points on the inner edges thereof. Theelements are semicircular in outline and of such area that they overlapone another at, their linear marginal edges so as to form a partitionextending completely across the passage and acting as a dam for theaggregates as will be more fully described hereinafter. In addition theelements E are twisted (see Fig. 8) to follow the same general helicalform of the blades, thus offering no impediment to movement of theaggregates inwardly of the drum during rotation of the blades in adirection to effect feeding of the aggregates to the forward end of thedrum. Also the elements E are located on the blades at a pointsufficiently spaced from the opening I8 so as not to interfere with freefiow of the aggregates into the drum when loading the latter through thestationary hopper l9.

In Figs. 2 and 6 the front drum portion I6 is shown provided with meansfor increasing turbulence of the aggregate received therein to eifectmore thorough mixing thereof, and thus producing a better quality ofconcrete, and also means for preventing balling of the aggregates (theaggregates forming into balls) and rendering the mix non-uniform anddifficult of expulsion by the blades.

The means for increasing turbulence comprises a plurality of fins 30, inthe present instance two, which are in the form of plates secured, as bywelding, at one end to the inner wall of the front drum portion It so asto extend inwardly toward the axis of the drum at different angles. Onefin is adjacent the flat end of the front drum portion [6, as shown inFig. 2, while the other is located further rearwardly within the drum.Such an arrangement disposes the fins to opposite sides of the lastconvolution of the blades B where, under rotation of the drum, theyoperate to lift and drop the aggregates and thus create a greatturbulence thereof.

The means for preventing balling of the aggregates comprises a pluralityof bars 3i, preferably angle bars, which are secured, as by Welding, tothe forward wall of the drum at one end and to the blade 13 at theother, so as to extend longitudinally in the drum and at differentpoints circumferentially therein. Only two such bars are here employedand the shorter one thereof is shown welded to one side of the adjacentfin 30 to provide an additional support for the latter. The longer barlikewise is welded to one side of the other fin 3-3, and to the end ofthe lade B.

The afore-described arrangement of bars 3! serves under rotation of thedrum, to intercept and separate the aggregates as they cascade from thewall of the drum and the blade 13 to prevent ballin thereof and thusinsure a uniform nix.

In operation of the mixer it will be understood that when charging thedrum with aggregates through the hopper iii, the drum is rotated in suchdirection that the blades B and Bi operate to mix the aggregates and atthe same time progressively move them forwardly in the drum. When thedrum is rotated in the reverse direction the blades function to feed themix rearwardly and discharge it from the opening 18.

During transit of the mixer to a job, the drum is rotated in thatdirection as when charging to eiiect constant mixing of the aggregates,since such mixing must be maintained to prevent setting of the resultantconcrete. In consequence the aggregates are being constantly cascaded,that is, lifted and dropped by the inner convolutions of the blade 13and the fins 30.

In travelling to a job the mixing drum is subject to sudden forwardmotions due to starting as well as accelerating the forward speed of thetruck while under way. It is these motions, particularly when the truckis ascending an incline, that, in a mixer with conventional helicalblades, cause the spillage of the aggregates, since the passage betweenthe blades allows the concrete to be thrown rearwardly and outwardly ofthe drum opening it. To reduce the possibility of such spillage, usersof the conventional mixer reduce the quantity of aggregates for anygiven charge considerably below the real capacity of the drum. Obviouslythis reduces the pay load.

In a mixer wherein the blades are provided with damming elements E, asin my invention, the drum can be charged to its full capacity withoutthe possibility of spillage during transit, inasmuch as the elementscompletely block off the passage P against the aggregates being thrownrearwardly and out of the opening :8 due to any forward movement of thetruck, and regardless of the degree of suddenness of such movement orthe inclination of the drum at the time it occurs. This blockingfunction of the elements is effective irrespective of the slumpcharacteristics of the mixture, and particularly if the slumpcharacteristics are high, because the overlapped arrangement of theelements provides a complete block-oif.

When rotation of the drum is reversed for a discharging operation theelements E function to confine the concrete on the blades .8 and Bi fora time sufficient to effect packing thereof resulting in a more positiveand rapid discharge of the concrete from the mixer. The net result isthat the drum can be completely discharged in less time than has beenheretofore possible.

In Figs. 9 and 11 I have shown the same mixer embodying a modified formof damming element El for preventing spillage when mixing aggregates oflow slump characteristics, that is, where the solidity of the mix issuch that accelerated forward movements of the truck must be extremelysudden to cause ejection of th concrete from the drum.

There are two of these elements El at corresponding points on the inneredges of the blades B and Bi, and as will be understood, they may beseparately formed and secured to the blades, or formed integral with theblades. They are located along the length of the blades at the samegeneral point as are the elements E in th other form of my invention,and so as to be disposed within the rear drum section I! and spacedinwardly from the opening l3.

The elements El are of arcuate form, helically twisted, and tapered fromend to end to correspond to the taper of the blades. Additionally, theyare reversely disposed lengthwise on the blades so as to coact in partlyblocking or damming the passage P. This construction and arrangement ofelements leaves an opening 33 (see Fig. between the elements throughwhich the shaft 2i! if lengthened to an open end of the drum and mountedto support the drum at both of its ends, could be extended withoutaltering the construction of the elements.

It has been found in practice that while the elements El block off thepassage P only partly, it is sufiicient to prevent spillage under anytravelling condition when mixing batches having low slumpcharacteristics. As with the elements E they do not interfere withcharging of the drum, and they function to prevent spilling of theconcrete from the blades in the same manner as the elements E and forthe same purpose of packing the concrete to accelerate its dischargefrom the drum.

It is to be understood that various changes and modifications may bemade herein both as to the shape of the mixing drum, the blades, thefins and the bars therein, and more particularly the form andarrangement of the damming elements in the drum, without departing fromthe spirit of my invention and the spirit and scope of the appendedclaims.

What I claim is:

1. A concrete mixer, including: a rotatable mixing drum having anintermediate cylindrical portion, a front conical portion which isclosed at its front end, and a rear conical portion which is open at itsrear end to provide a feeding and discharge opening for aggregates; amain helical blade fixed Within said drum and substantially coextensivein length therewith; a subsidiary helical blade fixed within th rearconical drum portion and extending part way into the cylindrical drumportion; and elements fixed on said blades at a point within the rearconical drum portion for blocking off the space between the blades atone point along th length thereof.

2. A concrete mixer, including: a rotatable mixing drum having a rearend portion; a pair of helical blades fixed at their outer edges to theinner wall of said portion to provide a straight passage leading to therear end of said portion; and a pair of elements fixed on the inneredges of said blades in alignment with the respective blade andextending inwardly therefrom to substantially span said passage.

3. A concrete mixer, including: a rotatable mixing drum the rear endportion of which is of truncated conical form; a pair of helical bladesfixed at their outer edges to the inner wall of said portion to providea straight passage leading to the rear end of said portion; and a pairof elements of substantially semi-circular outline having their curvededges fixed respectively to the inner edges of said blades in alignmenttherewith at diametrically opposite points between the ends of saidportion and their straight edges extending to opposite sides anddiametrically of the axis of said passage.

4. A concrete mixer, including: a rotatable mixing drum the rear endportion of which is of truncated conical form; a pair of helical bladesfixed at their outer edges to the inner wall of said portion to providea straight passage leading to the rear end of said portion; and a pairof elements of arcuate form, helically twisted, and tapered from end toend to correspond to the contour of the blades, the outer edges of theelements being fixed respectively to the inner edges of the blades atdiametrically opposed points and so that the elements are reverselydisposed lengthwise on the blades with their inner edges extending intosaid passage whereby the elements partly block off the passage.

5. A concrete mixer, including: a rotatable drum having an open end anda closed end; a helical blade fixed within the drum and extending intothe closed end of the drum; fins fixed at one end within the drumadjacent the closed end thereof and extending radially inward of thedrum; and bars fixed at their ends to the closed end of the drum and tosaid blade so as to extend longitudinally of the drum.

6. A concrete mixer as embodied in claim 5, wherein the bars are fixedbetween their ends to the fins.

JESSE R. CAS'I'ENDYCK.

REFERENCES CITED The following references are of record in th file ofthis patent: 8

UNITED STATES PATENTS Number

